Landslide Risk Demands Attention in Kadugannawa - Prof. Senaratne

Expert Calls for Comprehensive Survey to Prevent Future Landslides in Kadugannawa

A recent landslide in Ganethenna, Kadugannawa, which resulted in six fatalities, has highlighted the urgent need for a thorough geological assessment of the surrounding area. Dr. Athula Senaratne, a former Senior Professor of Geology at Peradeniya University, emphasized the importance of a comprehensive survey of a 400-acre area around the railway line and main road to mitigate future landslide risks.

During an inspection of the affected site, Dr. Senaratne explained the complex geological conditions that make the region vulnerable to landslides. He pointed out that while the main road and railway line are built on bedrock and not directly at risk of collapse, unstable sections of the wider area could still impact their structural integrity.

"When the railway was constructed, large tunnels were drilled through rock," he said. "It is possible that large rocks dislodged during the construction from Balana to Kadugannawa were pushed onto the lower slopes. These rocks could now be resting on the slope above the main road."

Dr. Senaratne warned against assuming the entire upper slope is solid bedrock. "We will get into trouble if we work with the belief that the upper slope is entirely bedrock. Therefore, we must study this area very meticulously," he urged. "The mountain recedes as rocks break off, which is how the natural slope is formed. We need to stabilize the at-risk rocks and make the slope safe."

He recalled a previous warning he issued in 2012, when he noted the risk of the main road subsiding. "What the Road Development Authority did was cover the cracks with tar. That is not effective. The road must be stabilized with concrete beams underneath or it will lead to major problems."

Fractures and Tree Roots Pose Additional Risks

Dr. Senaratne observed that some rocks on the slope below the railway line show fractures. He noted that tree roots had grown around the rock that fell onto a house and a shop. "Tree roots penetrate cracks in the bedrock. As they grow, the cracks widen, and sections break away from the parent rock. We cannot say if this will happen today or in 100 years."

He also identified another large, potentially unstable rock above the recent landslide site and recommended using drones for a more effective survey. "Drones can provide detailed imagery of the slope, helping us identify areas that require immediate attention."

Current Stabilisation Efforts Are Insufficient

According to Dr. Senaratne, the current stabilisation work at the landslide site covers only about 3% of the total risk area. "The primary threat exists in several locations along a two-kilometre stretch of the railway line and a 2.5-kilometre stretch of the main road."

He also stressed the need for a special investigation of the slope below the main road. "About one kilometre from the landslide site towards Kandy, a subsidence is visible on the slope. Instead of patchwork solutions, a proper study must be conducted," he asserted. "Technology is very advanced today, so permanent solutions can be implemented. The world has the necessary technology to fix these issues."

Human Activities Increase Risk

Dr. Senaratne called for an immediate halt to human activities on the slopes, citing unauthorised constructions for business expansion and the high-pressure pumping of water for vehicle washing as significant problems. "There are natural streams that flow down the slope. Some individuals block these streams to divert water under high pressure, which alters the natural water flow," he explained.

"This activity, combined with heavy rainfall, creates muddy conditions in the soil, causing rock fragments breaking from the parent rock to be pushed down the slope." He concluded by emphasizing the need for strict enforcement of laws to prevent future disasters. "If people do not obey the law, authorities must make decisions for the public good. Otherwise, a disaster far greater than this could occur in Kadugannawa in the future."